The present invention relates to missile control systems and, in particular, to a system for control of the thrust vector control (TVC) system in a ballistic missile. The invention relates more particularly to a control system for a gas-generator-powered turbohydraulic TVC system.
In a present ballistic missile system, hydraulically operated actuators control the orientation of the rocket motor nozzle to provide thrust in the proper direction. A solid-propellant gas generator drives a turbine which drives a centrifugal pump to provide hydraulic pressure to operate the actuators. An open-loop control system is used in which the components are sized so that both peak power and the full range of tolerances of all components are accounted for. A typical gas generator has a .+-.25 percent variation in burn rate due to temperature and propellant variations. In case the propellant burns too fast, extra fuel must be provided to maintain the burn for the required duration. In case the propellant burns too slow, the generator must be oversized to generate proper mass flow. This causes all other components to be oversized to protect against a faster burn rate. Additional tolerances in the turbine-driven pump unit, the servo-actuators, and the load cause a nominal system to provide almost a 100 percent performance margin and use twice as much gas as needed since the system is designed on a worst-on-worst basis. These factors combine to increase the weight of the system which reduces the missile's range.